Fiber reinforced composite material is known which is reinforced with fibers impregnated with resin. The fiber reinforced composite material is exemplified by CFRP (Carbon Fiber Reinforced Plastics). Since there is great merit in weight saving, such fiber reinforced composite material is applied to products such as aircraft structural members. As a molding method of the fiber reinforced composite material, there is a VaRTM (Vacuum assisted Resin Transfer Molding) in which laminated reinforcement fibers are impregnated with resin in a vacuum and the resin is cured. In a fiber reinforced composite material manufactured by the VaRTM, inherent defects such as a void and impregnation failure of resin may occur. In general, when the defect in the fiber reinforced composite material is repaired after curing, the strength of the repaired portion is reduced since reinforcement fibers are processed. A composite material manufacturing method is desired in which a repair is performed without reducing strength of a fiber reinforced composite material.
Japanese Patent Publication (JP-A-Heisei 07-137154) (conventional example 1) discloses a resin composite repair method with extremely-high repairing effect, capable of filling of resin by performing no or minimum additional process to a product. With respect to the resin injection repair method for resin composite, in a repair method in which resin is injected into a defect portion of a resin composite having a defect consisting of avoid with an opening portion, a connection jig including a communicating tube with a valve is attached via a sealant to a surface of the resin composite such that the communicating tube communicates with the opening portion in a airtight state, the communicating tube is connected to a pressure reducing device to reduce pressure in the void of the defect portion, and then resin is injected from the communicating tube.
Japanese Patent Publication (JP-P2003-39455A) (conventional example 2) discloses an RTM method which can easily mold an FRP structure having a complicated shape or a high-quality FRP structure with no portion of impregnation failure. In the RTM method, in which reinforcement base material is placed in a molding die having injection ports and depressurization ports, the upper surface of the molding die is covered and sealed up with an upper die or bag material, and then resin is injected from the injection ports while sucking air from the depressurization ports, when an impregnation failure portion is likely to remain in a molding product during the molding, the impregnation failure portion is filled up with resin by switching at least part of the depressurization ports to injection ports to inject resin before the completion of resin injection.
Japanese Patent Publication (JP-P2004-203021A) (conventional example 3) discloses a resin impregnation sensor/repair device which can easily detect (monitor) degree of resin impregnation and can repair an impregnation failure defect before resin is cured. The resin impregnation sensor/repair device has a tube which penetrates a bag film for covering fiber base material to be impregnated with liquid resin in a vacuum and to be put into the fiber base material, and a transparent airtight vessel in communication with a base end of the tube.
Japanese Patent Publication (JP-P2005-271247A) (conventional example 4) discloses an FRP reinforce/repair method which can perform reinforce/repair operations while restoring shapes and functions before repair, and guarantee quality by improving strength properties such as bonding strength and stability of the strength properties while maintaining an advantage that degree of freedom of a place of the operations is high. The FRP reinforce/repair method is characterized in that the FRP reinforce/repair method at least includes the following steps of (A) to (E): (A) a bonding layer covering step for covering with a bonding layer, an outer surface of a defect portion for which reinforcement and repair of FRP are desired; (B) a preform setting step for placing a preform, which at least includes reinforcement fiber base material, on the bonding layer; (C) a sealing step for connecting a depressurization suction port and a resin injection port to the preform and covering at least portions of the bonding layer and the preform with a bag material; (D) a resin impregnating step for depressurizing a cavity formed in the bag material and injecting resin from the resin injection port to impregnate the preform with resin; and (E) a curing step for curing the injected resin.
Japanese Patent Publication (JP-P2006-187897A) (conventional example 5) discloses a defect repair method for composite, which can prevent deterioration of after-repair quality and strength of a resin composite product by securely filling a void defect portion formed in the resin composite product with resin and can deal with various defect situations. The defect repair method for composite is a defect repair method for filling with resin, a void defect portion which has an opening portion and is formed in a resin composite product. The defect repair method for composite includes: a covering and sealing step for covering a surrounding region of the opening portion with a flexible covering material such that a specific space surrounded by the resin composite product and the covering material become airtight state; a vacuum step for discharging air from the specific space to cause pressure in the specific space to be a predetermined vacuum pressure; a resin accumulation process for providing a resin reservoir outside the covering material to accumulate liquid resin in the resin reservoir such that the liquid resin is adjacent to the opening portion across the covering material; a resin flowing step for making a resin inflow hole in a portion of the covering material, which is adjacent to the opening portion, and causing the liquid resin accumulated in the resin reservoir to flow into the void defect portion through the resin inflow hole and the opening portion due to the vacuum pressure inside the specific space; and a resin curing step for curing the resin which has flowed into the void defect portion.